Abstract The inclusion of the terrestrial nitrogen cycle in Earth system models (ESMs) represents a major advance, yet its role in fully coupled climate–carbon–nitrogen dynamics remains underexplored. Using MAGICC-CNit to emulate CMIP6 ESMs, we present the first emission-driven, probabilistic cross-ESM projections of climate–carbon–nitrogen interactions and global carbon budgets across SSP1-2.6 to SSP5-8.5 scenarios.